Texas medical authorities have filed new charges against a controversial Houston doctor who was the subject of a USA TODAY investigation.

In a complaint filed Dec. 11, the Texas Medical Board said Stanislaw Burzynski marketed his experimental cancer therapies online and in news releases in a way that is "false, misleading and violated federal law."

In a statement Wednesday, the Burzynski Clinic dismissed the charges as "frivolous," arguing that he has a constitutional right to make truthful statements about his research.

The charges are the latest attempt by Texas medical authorities to discipline Burzynski, 70, who has wrangled with the state board since the 1980s over his use of experimental drugs that he claims can cure certain cancers.

According to the National Cancer Institute, Burzynski has no definitive evidence to support his claims about the drugs, called antineoplastons, which are not approved by the Food and Drug Administration. According to the NCI, "no randomized, controlled trials showing the effectiveness of antineoplastons have been published in peer-reviewed scientific journals."

The FDA allowed Burzynski to test antineoplastons through a clinical trial from 1996 to 2013, when the agency put the trial on hold over safety concerns.

The new Texas complaint is based on action taken by the FDA in October 2012, when the agency notified Burzynski that his claims about antineoplastons violated the federal Food, Drug and Cosmetic Act. The law prohibits drugmakers from making claims about the safety or effectiveness of unapproved drugs.

The FDA ordered Burzynski to stop making these claims, which had been repeated on his website, in news releases and in videos on his YouTube channel.

In its complaint, the Texas Medical Board charges that Burzynski misled consumers. Burzynski "never informed consumers that antineoplastons have not been 'proven' to cure cancer, and he only stated that they were 'not approved by the FDA.' "

The Texas board listed several "aggravating factors" in Burzynski's case, including "increased potential for harm to the public, prior similar violations and previous disciplinary action by the board."

The board suspended Burzynski's license in 1994, saying he used antineoplastons illegally to treat patients with cancer and AIDS, a violation of both state and federal law. The board then held the suspension, instead placing him on probation until 2004.

In December, the FDA issued a strongly worded warning letter to Burzynski, saying he inflated the success rates of his clinical trials, neglected to report serious side effects and failed to prevent patients from repeatedly overdosing. According to the FDA, Burzynski's failure to keep accurate patient records "raises concerns about subject safety and data integrity, as well as concerns about the adequacy of safeguards in place at your site to protect patients."

If Burzynski fails to adequately address the FDA's most recent concerns, the agency could terminate his clinical trial, disqualify Burzynski from conducting FDA research, issue a civil fine or pursue criminal charges, according to FDA regulations.

The FDA does not have the power to revoke Burzynski's license to practice medicine. Only Texas authorities could bar Burzynski from treating patients.

A date has not been set for Burzynski's hearing with the medical board.

In a legal response filed Jan. 2, Burzynski's attorney, Richard Jaffe, noted that the FDA's 2012 letter was not an official warning. "The informal letter which is the basis of this case is non-binding and does not constitute final agency action," Jaffe wrote. "Federal courts have held that such letters are not even admissible."

In an email, Jaffe said, "Any attempt to restrict truthful speech under the authority of a restriction on promotion of an investigational drug will be rejected by the courts under First Amendment grounds."